A well can include a borehole (or “wellbore”) that is drilled into the earth to provide access to a geologic formation below the earth's surface (or “subsurface formation”). A portion of a subsurface formation that contains (or at least is expected to contain) mineral deposits is often referred to as a “reservoir”. A reservoir that contains hydrocarbon, such as oil and gas, is often referred to as a “hydrocarbon reservoir”. A well can facilitate the extraction of natural resources, such as hydrocarbons, from a subsurface formation, facilitate the injection of fluids into the subsurface formation, and facilitate the evaluation and monitoring of the subsurface formation. In the petroleum industry, wells are often drilled to extract (or “produce”) hydrocarbons, such as oil and gas, from hydrocarbon reservoirs located in subsurface formations. The term “oil well” is often used to describe a well designed to produce oil. In the case of an oil well, some natural gas is typically produced along with oil. Wells producing both oil and natural gas are sometimes referred to as “oil and gas wells” or “oil wells.” The term “gas well” is normally reserved to describe a well designed to produce primarily natural gas. The term “hydrocarbon well” is sometimes used to describe both oil and gas wells.
Creating a hydrocarbon well typically involves several stages, including drilling, completion and production. The drilling stage typically involves drilling a wellbore into a hydrocarbon reservoir in an effort to access the hydrocarbons trapped in the reservoir. The drilling process is often facilitated by a drilling rig that sits at the earth's surface. The drilling rig provides for operating a drill bit; hoisting, lowering and turning drill pipe and tools; circulating drilling fluids; and generally controlling operations in the wellbore (or “down-hole operations”). The completion stage typically involves making the well ready to produce hydrocarbons. In some instances, the completion stage includes lining portions of the wellbore and pumping fluids into the well to fracture, clean or otherwise prepare the reservoir to produce the hydrocarbons. The production stage typically involves extracting and capturing (or “producing”) hydrocarbons from the reservoir via the well. During the production stage, the drilling rig is normally removed and replaced with a collection of valves (often referred to as a “production tree” or a “Christmas tree”) that regulate pressure in the wellbore, control production flow from the wellbore, and provide access to the wellbore in the case further completion work is needed. A pump jack or other mechanism can provide lift that assists in extracting hydrocarbons from the reservoir, especially in instances where the pressure in the well is so low that the hydrocarbons do not flow freely up the wellbore to the surface. Flow from an outlet valve of the production tree is normally coupled to a distribution network, such as pipelines, storage tanks, and transport vehicles that transport the production to refineries, export terminals, and so forth.
In many instances, multiple wells are drilled into a reservoir. These wells are often referred to collectively as a “field” of wells. In an effort to efficiently produce hydrocarbons from a reservoir, well operators often commit a large amount of time and effort into generating field development plans (FDPs) that define various aspects of a field, including the number and locations of wells, paths (or “trajectories”) for the wellbores of the wells, parameters for operating the wells and so forth. An FDP for a field is often based on knowledge of the underlying formation that is obtained, for example, via seismic imaging, laboratory testing of samples extracted from the formation, testing of existing wells, and so forth. Well operators typically drill and operate wells according to an FDP. For example, where an FDP specifies well locations and well trajectories for a number of wells, the operator may drill each of the wells at a respective one of the well locations and with the corresponding well trajectory.
In some instances, well locations are determined based on “drainage regions” for the wells. The drainage region for a hydrocarbon well can define the area within the hydrocarbon reservoir from which the well is expected to produce hydrocarbons. Hydrocarbons are expected to flow from the drainage region, into the wellbore during production operations. Thus, it can be expected that all or almost all of the production for a well will originate from within the drainage region for the well, although some production may migrate into the drainage region from surrounding portions of the reservoir. A drainage region for a well may be defined, for example, by a radius around the wellbore. This radius can define what is referred to as the “drainage boundary” for the well.
In many instances, development of an FDP takes into account the drainage regions for wells in the field when positioning the wells. For example, when developing an FDP an operator may position wells so that they are close enough to cover the entirety of the reservoir, but not so close that their drainage regions overlap significantly, resulting in the wells competing for production. The positioning of the wells often involves a consideration of the distance between adjacent wells (or “well spacing”).